1. Technical Field
This disclosure relates to semiconductor devices and fabrication methods, and more particularly, to multilevel fuse structures and fabrication methods.
2. Description of the Related Art
Semiconductor devices include on-chip integrated circuits. These integrated circuits may include fuses. Fuses are employed on a semiconductor device to enable or disable portions of a circuit. Fuses are typically classified as two types: laser blown and electrical fuses. Both laser blown and electrical fuses are typically located near the surface of the semiconductor device so that fuses can be blown without damage to underlying integrated circuits. As chip density increases, however, the distance between fuses (fuse pitch) is forced to become smaller. When a fuse is blown, damage may be caused to neighboring fuses or wires.
Referring to FIGS. 1A and 1B, a semiconductor layout 10 shows two laser blowable fuses 12 and 14 adjacent to one another. Fuses 12 and 14 of FIG. 1A each include a thermal pad 16, which melts from laser heat to open a fuse. For lower fuse pitches (P), a laser beam 13 aimed at fuse 12 could cause damage to fuse 14. Damage to fuse 14 may also be caused when fuse 12 is blown or due to cracks, which may propagate to fuse 14 as a result of the blowing process.
Therefore, a need exists for a fuse structure and method for fabrication, which provides for smaller spacing between fuses and protects neighboring fuses when a fuse is blown.
A semiconductor device has a first conductor and a second conductor for fuse terminals. A fuse portion is disposed on a different level relative to both the first conductor and the second conductor. A first contact connects the fuse portion to the first conductor, and a second contact connects the fuse portion to the second conductor.
In other embodiments, the fuse portion may include tungsten. The first conductor may be disposed on a different level than the second conductor. The fuse portion may be disposed in a terminal via window. The fuse portion may include a thermal pad.
Another semiconductor device of the present invention includes a plurality of fuses disposed in a fuse region. Each fuse includes a first conductor, a second conductor, and a fuse portion disposed on a different level relative to both the first conductor and the second conductor. A first contact connects the fuse portion to the first conductor, and a second contact connects the fuse portion to the second conductor wherein each fuse portion is offset from adjacent fuse portions.
In other embodiments, the fuse portion preferably includes tungsten. The first conductors are preferably disposed on a different level than the second conductors. The fuse portions may be disposed in a terminal via window. Each fuse portion may be next to one of the first conductor and the second conductor of adjacent fuses, and each fuse portion may be disposed on a different level than the one of the first conductor and the second conductor of adjacent fuses. The fuse portions may be formed on a plurality of different levels. The plurality of different levels may include two and the fuse portions may alternate between the two different levels. The fuse portions may include a thermal pad.
Another semiconductor device of the present invention, includes a plurality of fuses disposed within a terminal via window. Each fuse includes a first conductor, a second conductor disposed on a level different from the first conductor, and a fuse portion disposed on a same level as the first conductor and connected to the first conductor. A first contact connects the fuse portion to the second conductor wherein every other fuse portion is offset to an opposite side of the terminal view from adjacent fuse portions, and every other fuse portion is adjacent to the second conductor of an adjacent fuse. In other embodiments, the fuse portion preferably includes tungsten. The fuse portion may include a thermal pad.
These and other objects, features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.